Catalytic Asymmetric Deprotonation Using a Ligand Exchange Approach

A novel ligand exchange approach to catalytic asymmetric deprotonation-electrophilic trapping has been developed that uses 1.3 equiv of s-BuLi, 0.06-0.2 equiv of chiral diamine ((-)-sparteine or a (+)-sparteine surrogate), and 1.2 equiv of achiral bispidine. The methodology is illustrated with a range of examples and gives access to either enantiomer of useful chiral products in good yields using substoichiometric amounts of chiral diamines.